LOPEZ-BAUTISTA, JUAN M.*, DONALD KAPRAUN, DEBRA A. WATERS, AND RUSSELL L. CHAPMAN. Department of Biology, University of Louisiana at Lafayette, Lafayette, LA, 70504 (Lopez-Bautista), Department of Biological Sciences, University of North Carolina, Wilmington, NC (Kapraun), Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803 (Waters and Chapman). - Nuclear DNA quantification and the life cycle in Cephaleuros parasiticus (Trentepohliales, Chlorophyta).
Microspectrophotometry with the DNA-localizing fluorochrome DAPI was
used to quantify nuclear DNA content in eight species representing
three genera of the subaerial green algal order Trentepohliales
(Chlorophyta). Comparisons of mean fluorescence intensity (If) values
of algal nuclear genomes to those of chicken erythrocytes (RBC)
resulted in an estimate of 1.1-4.1 pg for the algae. DNA levels in
Cephaleuros parasiticus Karsten for 2C nuclei in gametophytic
phase closely approximate 50% of the 4C values in the sporophytic
phase, confirming previous observations based on culture and
ultrastructural studies on the presumptive sexual life cycle in this
genus. The alternation of generations in this species was not
indicated in the original description by Karsten or in any subsequent
studies. Genome quantification data for eight trentepohlialean taxa
suggest a doubling sequence for nuclear DNA contents. This phenomenon
might reflect the presence of a polyploid series in the order
Trentepohliales
Key words: C-value
> >genome quantification, C-value, Cephaleuros, Chlorophyta, DAPI, nuclear genome quantification, Trentepohliales